A remote keyless entry system facilitates unlocking doors of a vehicle using a key fob. They key fob send a message that includes an authentication token and a counter value to a wireless receiver coupled to a body control module. The body control module unlocks the doors if the authentication token and the counter value are valid. Because the driver may press a button on the key fob when the key fob is out of range of the vehicle, the counter value is valid if it is within an acceptable range of an expected value. To break into a vehicle, a hacker (a) jams the radio frequency used by the remote keyless entry system so that a first message is not received by the wireless receiver, and (b) intercepts the first message with the authentication token and a first valid counter value. Thinking that the wireless receiver may not have been in range, often the driver presses the button on the key fob again. The key fob sends a second message with the authentication token and a second value counter value. The hack intercepts the second message and broadcasts the first message to the vehicle. As a result, the hacker obtains the second message that may be used to unlock the vehicle door at a later time when the driver is not present. This is referred to as a jam intercept and replay attack.